The invention relates to a printed circuit board with a meta layer arranged on its lower side and (high frequency HF) components arranged on its upper side, which components are connected by their input and/or output sides to HF sources, HF loads, or other HF components via microribbon lines and can be connected to a DC current source via a separate connection line.
Known printed circuit boards of this kind have an insulating support plate (substrate) on whose upper side a first electrode is arranged for forming said microribbon lines ("Integrierte Mikrowellenschaltungen" by Reinmut K. Hoffmann, Springer Verlag 1983, pp. 142-144). A second electrode for forming the microribbon lines is constructed as a metallization over the entire surface area of the lower side of the support plate. This metal layer also serves to drain off the DC current. The high-frequency (HF) components arranged on the upper side of the printed circuit board and connected to the microribbon lines are partly connected to the metal layer on the lower side by means of direct connections through the insulating plate. The HF signals are conducted to the gates of the HF components via the microribbon lines. To achieve a low-loss, low-reflection transmission of the HF energy, the metal layer is not interrupted at the lower side of the microribbon lines and has at least a width which is approximately the same as up to three times the width of the connection line on the upper side. For the same reason, a connection between the HF ground connection points of the HF components and the metal layer on the lower side is required to be direct and as short as possible. The currents passed by the HF components have a frequency at the input side of, for example, approximately 10 GHz to 13 GHz, and at the output side a frequency of, for example, 1 GHz to 3 GHz in the case in which the HF component is a frequency converter.
The individual HF components are provided with a DC current by a DC voltage source independently of the high-frequency currents, which DC current enters the current supply inputs of the HF components and is drained off into the metal ground layer at the lower side of the printed circuit board via direct connection lines of the HF components through the insulating plate. A DC voltage source of, for example, 6 V serves to supply the current in known constructions, where, for example, two HF components, for example ICs, are connected in parallel as far as the DC currents are concerned, so that each component receives a DC voltage of 6 V and, for example, a current of 100 mA flows through each component. This means that the common supply line for the two HF components passes a current of 200 mA. Such a current value, however, is too high for several applications. A solution could be that a voltage source of, for example, 12 V is chosen and that the two HF components are connected in series for the DC current, so that each HF component receives a voltage of 6 V. If such a construction were to be realized on a microribbon printed circuit board as described above, difficulties would arise on account of the metal layer at the lower side of the printed circuit board which is common to all components and essential for microribbon connection lines.